Optical scanning device



N. o. a. CALDiR an...

imea oa. 1s. v

I INVENTOFS mesa. mvm RITCHIE cam FIG. 2

" omcanscanmcnmcn pa e; nanometre-career; Crowley, Pieter Schagen,

Salfords,'11ar Redhill, and Christopher Haly Toswill,

f United States Patent Reigate, England, by memo assignment, to I North American Philips 'N.Y., a of Delaware.

EiledOcL19,i956,Sei*.No. 615,981

V I V Claimpt-iority, application Gm Britain Oct. to less a coin (or. its-4o; I This invention relates to scanning for display 'ing images, more especially images composedin ao-Q 1 cordance with a raster oi parallel lines obtained by line and frame scans as, for example, in television display I systems.

In televiison apparatus employing a rectangular raster the relatively slow frame scan by mechanical means in order to simpliiy other problems, and such circumstances 2 may arise in the practical application of colour televisionv due to the greater complexity of the display requrrein is an object of m; present invention. to provide an improvedscanning device for displaying images.

A scanning device accordingto one aspe'ctof-thc invention comprises in cornbinationa rotatable carrier'or support carrying a plurality of similar cylindrical or substantially cylindricallenses which have the gcneratriccs of their curved surfaces parallel to the axis of rotation of said 'carrier and which lenses are similarly disposed in relation to such axis, stationary cathode ray tube means within said carrier and within the paths of said lenses for producing a source of light of ponit or spot form animated by repetitive motion along ,a substantially or generally rectilinear path'constituting aline scan on a stationary or approximately stationary path parallel to rt asswtt c Patented Oct. 13, teen 2 r thccasewheretheimageismagnifiaibymqfilfli positioned between the can'ier'and an observer: potititm, in a device according to the second Of the'inven tion thelinescanlightsourcewithinthecarrierwill be 'eccentrimlly disposed within the carrieron thls e of.

the axis remote from the viewing position server. However, in the case'where the image is viewed f in a mirror located behind the will be determined with respect to aaline scan source will be disposed eccenMy thecarrieronthesideoftheaxisrernotefromtbemitmlai The efiect of the cccentr-icityinallthesecasesintranet? I duce a travelling image to be viewed by an 20. Q it may in certain circumstances be desirable to effect which image has a curvature which is its than curvature of the pathof the lenses,"and this property will be explained hereinafter.

When the invention'is apnliedto theproduction of an image in a television displaysystem the image is seat by viewing the light source through successive lenses and such a system, being a viewing system as opposed to a projection system, is advantageous over projection 4 systems inasmuch as. the apparent brightness of the individual lines is equal to the apparent brightness ofv tho line source itself. The width of the line image seat will be smaller than the .width of the source but 32;:

between the lines of the raster can be avoided by ingthe widthof the source. a

With a television display system as indicated above and employing a rectilinear light source, the numbu' of lenses depends on the desired viewing angle and also on the position oi the light source within the rotary lurs can- 1 tier structure. Moreover, these parameters are also related to the cross-section of the lenses. Thus, to ob.- tain a wide vertical viewingangle it is necessary to have lenses having a short focal length; lenses. suitable from this point of view are right-cylindrical lenses having acircular cross-section, and in certain circumstances it may the axis of rotation of said carrier, and opaque maslting means extending betwecnadjacent lenses for preventing viewing of-thc line scan source except through one 1 or other of The term cylindrical lens is used herein to denote a lens having a form defined byrone or more curved surfaces generated by the motion of a rectilinear generattix maintained at a constant orientation and having a croma section normal to said generatrix comprising one or more curved lines which do not exhibit amathematicalpointof inflection; or defined by such a curved surface and a plane surface parallel to the generatrix thereof. firch be desirable to reduce even further the focal distance by" giving the lenses an elliptical cross-section having its major axis co-planar with the axis of rotation of the vice. Such increase inthe viewing angle allows ro duction of the diameter of the-lens path for a' picture height. e

lenses are thus not restricted to having a circular or elliptical cross-section and may for example be doubleconvex or piano-convex. In one preferred example the cross-section of a lens is a complete circle thus giving the lens a rod form, which is convenient from a manufac turing point of view.

A scanning device according to a second aspect of the invention comprises in addition to the combination afore to luminesce in the basic colours,'cr dot sequentially.

described eccentric disposition of the line scan source It is convenient, when the invention is applied to-teb vision, to arrange that the length of the cylindritml exceeds the length of the line scan "while the distance be tween adjacent lenses is equal or approximately equal to the-length of the frame scam In the case of a tr'i-chrome colour television the rectilinear light source. may include means for dis playing the necessary colour components as well as the variation of light intensity of the picture and this may 7 be done by various known methods of colour displaysud: as, for example, simultaneous or sequential line of three adjacent strips of luminescent material adapted Alternatively, frame sequential display may be with a black and, white source by mounting a colour filter. across each of the cylindrical lenses or by said lenses so a to enable them to act as colour finer:

- Preferred embodiments of the invention ft! 0 television receivers with vertical frame scan will now-be described by way of example with reference to the accompanying diagrammatic drawings.

In the drawings:

Figure 1 shows a part perspective view of a carriu' drum carrying four cylindricallcnses, s

Figure 2 illustrates the formation and position of the image produced on the rotation ofsuch a drum,

Figure 3 illustrates a distortional effect of this image, and

Figure- 4 shows means for correcting for such fiect.

5 neceaary for matching at 360- Syncbronisationoithorotatingc'arrierwith theinput' anit the primary colours quate brightness.

3. Adevic'oassetforth colon.

signalsmnbeachievedhywmparingthephaseofasawtooth wave generated as the carrier rotates with the phase of the frame synchronising pulses. Any variation in phase may be employed to cause a corresponding t "change in the degee of saturation of a satnrable reactor controlled device governing an motor driving the V shaft of the carrier. The saw-tooth wave may be gen-' erated as a'suitably'shaped' rotor on the shaft of, the

acoil-wotmd is claimed-is:

1- An optical mannin support a plurality of spaced substantially cylindrical.

'lenses mounted on said support and extending substantially parallel to each other and to the axis'of rotation of 1 said support, means comprising a phosphoristrip fixedly mounted within'the support and extendingparallel to" the said axis of rotation cooperating with amodulated electron beam for producing a scanning line extending substantially parallel to the said axis of rotation, and lightopaque means extending between the spacer! lenses, said scanning line being viewable by an external observer along a line of view extending through said lenses, said phosphor strip being located between the axis and a point more remote from the observer than u-shaped stator. g device a rotatable V on the lineof view 2. An optiml scanmng. device comprising a rotatable suPP I't, a. plurality of spaced spbstantiallyecylindfical lenses mountai on said support along a generally cylindrical surface coaxial with the axis of rotation of said support so as to extend substantially parallel to each other and to the of rotation, a cathode ray type of electron device fixedly mounted within the support and comprising a phosphor strip extending parallel to the said axis of rotation cooperating with a modulated electron marmprodncing a scanning line of lightextending suhstantially'parallel to but spaced from the said a is'of rotation; said scanning line being viewable by an external-observer along a'line of view extending through said lenses, said phosphor strip being located at a point on theline of view; relative to the observer, beyond the axis, and light-opaque means extending between the spaced lenticular elements so as to prevent external oh- 5 servanceotthelineoflightexceptthroughalem.

2, wherein them ray device has a screen constituted of plurah adjacent stripes of luminescent material lumineecing in plural 4.Anoptical scanningdevicecomprising ahollow cylindrical rotatable support, a plurality of spaced substantially cylindrical straight rod-like lenses mounted Ollthe surface of said support and extending substantially parallel to each other and concentric with the axis of rotation of said support,- a cathode ray tube fixedly mounted within the support and comprising a phosphor v strip extending parallel to thesaid axis of rotation oooper' ating with a modulated electron beam for producing a sub- 'stantially stationary rectilinear scanning line of. light ex tending substantially parallel to but spaced from the said axis of rotation, said scanning line being viewable by an external observer along a. line of view'extending said lenses, said phosphor strip being located at a on the line of view, relative to the observer,'beyond the axis, and light-opaque means extending between thespaoed lenses so as to prevent external observanoeof the light except through a lens.

5. A device as setforth in claim 4 have a cireularerososection.

6. A device as set forth in claim 4- where have an elliptical cross-section.

ucing aide 7. A device as set forth in claim 4 for prod -8. A device as set forth in claim 4 wherein the total number of lenses is not less than than four.

ReferencesCitedinthefile-ofthis a UNITED STATES PATEN'I'S Burr 1' "Petenzf'm. 2 ,957,04 e

I COTIBCtBd below.

I column; 5, line 45, for "lent-.1

Attcsting Offi'cer v It is hereby certifid'that erroiap peaxeiflfiheebovehuhbered per! ent requiring correction and that thesaid, Letters Patent shoulci read a:

Column 2, line 5, fer "-t.hsid'e" reed thersidecu-lar elem-enns'f read lenses Signed and sealed this At h day of Jul (smm I W ERNEST'W. I 1 V DAVIDLLADD I e 5 commissi w iram UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent M0,. 2,957,044 I October 18, 1960 Nigel David Ritchie Calder et a1 It is hereby certified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 5 for "th side" read the side column 5, line 45, for "lenticular elements" read lenses Signed and sealed this 4th day of July 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patent: 

